Means for scavenging pneumatic conveying systems



H. R- PU RSEL Feb. 1, 1955' MEANS FOR SCAVENGING PNEUMATIC CONVEYING SYSTEMS Filed Oct. 5,. I952 QH-..||| lllllllll ll INVENTOR.

H HROLD R- Pu 125E!- BY W ATTORNEY United States Patent IWEANS FOR SCAVENGING PNEUMATIC CONVEYING SYSTEMS larold R. Pursel, Philadelphia, Pa., assignor to Beaumont Birch Company, Philadelphia, Pa., a corporation of Pennsylvania Application October 3, 1952, Serial No. 312,949

12 Claims. (Cl. 302-17) This invention relates generally to bulk materials handling systems of the vacuum type and is more particularly concerned with an improved construction which increases the capacity thereof.

When a material is to be handled in bulk and its nature permits entrainment thereof in a fluid stream, it may be advantageous to employ a vacuum type conveying system. For example, boiler house ashes are commonly handled by such a system, the latter usually including a horizontal section of conveyor pipe provided with air and ash intakes, a riser section of conveyor pipe, an air and ash separator, an air exhauster and means for starting and stopping the flow of air through the system. The air exhauster acts to draw a stream of air and ashes through the conveying system, the ashes being collected in the separator. Normally, the latter has a capacity limited to the quantity of ashes collected in several min utes, and, consequently, the air flow through the system is stopped intermittently to permit discharge of the ashes collected by the separator.

The arrangement just described, however, has not been entirely satisfactory. Each time the aforementioned stoppage occurs, some ash traveling in the riser section of conveyor pipe drops out of air suspension and accumulates in the elbow at the foot of the riser section. When the ash collected in the separator has been discharged and the flow of air is to be resumed, the ash packed in the elbow impedes the flow of air and delays restoration thereof to normal volume and velocity. The time required to entrain the packed ash and to restore full capacity conveying from the ash intake is therefore increased. Furthermore, the elbow sometimes packs so solidly that it must be cleaned out manually, which, of course, contributes to a reduction in overall conveying capacity.

Accordingly, it is an object of this invention to provide a bulk materials handling system of the vacuum type with means for scavenging the material passing through a generally vertical section of the conveyor conduit when the flow of fluid through the system is about to be stopped.

Another object of the present invention is to provide a bulk materials handling system of the vacuum type with means for by-passing the materials inlet for scavenging the material passing through a generally vertical section of the conveyor when the flow of air through the system is about to be stopped.

Still another object of the present invention is to provide a bulk materials handling system of the vacuum type with valve means proximate the upstream end of a generally vertical section of the conveyor conduit for bypassing the materials inlet, the timing being such that the valve becomes elfective for by-passing of the materials inlet shortly before the flow of conveying fluid through the system is stopped.

And accordingly, this invention may be considered as comprising the various features of construction and/or combination affording one or more of the above stated and other objects and advantages as hereinafter more particularly pointed out in the following detailed description and appended claims, reference being had to the acfiorlilpanying drawings of an illustrative apparatus, in w 1c Figure l is a sectional elevation through a boiler house showing a conveyor system incorporating the present invention; and

Figure 2 is an enlarged sectional elevation on line ice 2-2 of Figure 1 showing part of the conveyor system of Figure 1, parts being omitted or broken away for the sake of clarity.

Referring particularly to Figure 1, it will be seen that by way of illustration a conveyor system incorporating the present invention is shown installed in a boiler house provided with outer vertical walls 11-11 having a basement 12, boiler room floor 13, an upper floor '14 and a roof 16 therebetween. A battery of boilers 17 are suitably installed in the boiler room in spaced relation to one another, and associated with boilers 17 are ash hoppers 18 depending from boiler room floor 13 and equipped with ash discharge means 12 extending down into a trench 21 provided in basement 12.

The conveyor system comprises essentially a conveyor conduit equipped with a scavenger valve 22 and in communication with an exhauster 23 through a separator 24. The conveyor conduit is made up of sections of pipe suitably secured together and affording a horizontal air intake section 26, another horizontal section 27 adjoining section 26 and disposed normal thereto, a section 28 adjoining section 2'7 and rising vertically therefrom, and still another horizontal section 29 adjoining section 28. The horizontal section 26 runs along trench 21 beneath the ash discharge means 19. The horizontal section 27 also runs along the trench 21 but the end thereof proximate the riser 28 extends beyond the associated boiler house wall (not shown) to permit section 28 to rise outside the building for connection to the separator 22 through the horizontal section 29.

The horizontal section 26 is open to atmosphere at the end thereof remote from horizontal section 27, as at 31, and spaced intermediate portions thereof are suitably apertured for communication with ash hopper discharge means 19. Disposed in section 26 intermediate the connection thereof with section 27 and the ash discharge means 19 nearest section 27 is a cut-off gate 32 operated by means of wheel 33. Preferably, the open end 31 of the air intake section 26 is fitted with a sheek valve (not shown) suitably designed to permit free intake of air and prevent any back flow thereof.

The section 27 communicates with atmosphere through a short section of conduit 34 rising vertically from a portion thereof proximate the riser 28. The section 34 is provided with a flange 36 disposed in a horizontal plane, and seated on flange 36 is a valve plate 37 actuated by means to be described hereinafter.

The separator 24 and the exhauster 23 are each of a conventional type wherein the latter is operable to draw air and ash through the conveyor conduit and into the separator 24 where the air and ash are separated, the ashes being collected for discharge through a gate 38, and the air being discharged through the exhauster 23, all by means not shown or described in detail for the reason that the present invention is not concerned with such means per se and a more detailed description is not deemed necessary to a full understanding of the present invention.

The means referred to hereinabove for actuating valve plate 37 comprises a pneumatic piston 39 controlled by a valve 41 which is actuated by an electro-magnetic solenoid unit 42. The piston 39 is disposed directly over valve plate 37 and is mounted in a cylinder 43 fixedly secured to conveyor conduit section 27 by a suitable structural frame 44. The piston 39 and the head 40 thereof are disposed thereby for vertical reciprocation, and the lower end portion of piston 39 is secured to valve plate 37 for movement of the latter therewith between the full and broken line positions thereof shown in Figure 2, any suitagge means being provided to limit the stroke of piston The valve 41 for controlling the pneumatic piston 39 comprises an outer casing 46 mounting the electro-magnetic solenoid unit 42. The latter being a conventional type having a core (not shown) embraced by a coil, the former moving axially upward when the latter is energized. Rigldly terminally secured, this core is a rod 47 which depends therefrom and projects through the top of outer casing 46 and extends downwardly along one wall thereof, and which is normally urged downward as by a spring 48. The lower end portion and an intermediate portion of rod 47 are provided respectively with enlarged heads 49 and 51 which slidably engage the walls of an outlet chamber 52 of the valve 41 defined by the vertically spaced heads 49 and 51, the portion of casing 46 proximate rod 47 and an inner wall 53, the latter and the portion of outer casing 46 remote from rod 47 being spaced apart to form an inlet chamber 54. A pair of conduits 56 and 57 are connected to valve 41 for placing the inlet chamber 54 and the outlet chamber 52 in communication respectively with the supply and return channels of an air compressor, and another pair of conduits 58 and 59 communicate respectively with the upper and lower end portions of cylinder 43. The openings of the conduits 58 and 59 into the casing 46 are disposed so that in the position of rod 47 shown in Figure 2 the conduit 58 communicates with the inlet chamber 54 and the conduit 59 communicates with the outlet chamber 52, and are further disposed so that when the rod 47 is shifted upward under the influence of electromagnetic solenoid unit 42 the enlarged heads 49 and 51 are so positioned that the conduit 58 communicates with the outlet chamber 52 and the conduit 59 communicating with the inlet chamber 54.

It will be understood, of course, that the electromagnetic solenoid unit 42 is suitably connected in electric circuit with means which times the operation thereof in relation to the flow of air through the conveyor conduit and the operation of the discharge gate 33. A detailed description of the electric circuit is omitted as it is deemed unnecessary for a full understanding of the present inventron.

In the operation of the apparatus, the exhauster 23 functions to create a vacuum which draws a stream of air into the conveyor conduit through the in et or open end 31 of section 26. As the stream of air passes through the section 26 it draws the ash through the apertures or material inlets communicating with discharge means 19. Thus, the ash becomes entrained in the stream of air and travels therewith through the conveyor conduit to the separator 23, the latter functioning to separate the ash from the air. In this connection it will be noted that in this stage of the operation the valve plate 37 is firmly seated on flange 36 so that communication of the conveyor conduit with atmosphere through section 34 is cut off. The ash is collected in the bottom of the separator, and the air is discharged through the exhauster. When the capacity of the separator is reached, the electric control means referred to hereinbefore for timing the operation of the electro-magnetic solenoid unit 42 acts to stop the flow of air through the conveyor conduit and the separator and to open the discharge gate 38 for discharging the collected ash. However, the arrangement is such that at a selected time before the flow of air through the conveyor conduit and the separator ceases and the discharge gate 38 opens, the electro-magnetic solenoid unit 42 is energized.

Prior to such energization, i. e., while the scavenger valve 22 is closed and the ash is being conveyed from the ash discharge means 19 to the separator 24, the rod 47 is positioned as shown in Figure 2, and in this condition of the apparatus compressed air is supplied to the top of the cylinder 43 through the inlet conduit 56, chamber 54 and conduit 58, thus acting against the top of piston head 40 to keep the piston 39 and the valve plate 37 in the full line position thereof shown in Figure 2, wherein the latter is seated firmly on flange 36. When the electromagnetic solenoid unit 42 is energized, the core thereof (not shown) moves upward and rod 47 moves therewith against the force of spring 43 so that the heads 49 and 51 are positioned for communication of conduit 58 with the outlet chamber 52 and for communication of conduit 59 with the inlet chamber 54, and in this condition of the apparatus compressed air is supplied to the bottom of the cylinder 43 through the inlet conduit 56, inlet chamber 54 and conduit 59, thus acting against the bottom of piston head 40 to shift piston 43 and the valve plate 37 upwardly so that the latter assumes the broken line position thereof shown in Figure 2. In this connection, when the piston 43 is shifted from its elevated position to the position thereof shown in Figure 2, which movement is effected in the same manner as described hereinabove for seating valve plate 37 firmly on flange 36, the rod 47 is in the full line position of Figure 2, and the air in the bottom of the cylinder 43 under the piston head 40 is exhausted through conduit 59, chamber 52, and

outlet conduit 57 to permit movement of the piston 39. When the piston 39 is shifted upwardly again, the rod 47 is in such position that heads 49 and 51 are positioned for communication of conduit 58 with the outlet chamber 52 and for communication of conduit 59 with the inlet chamber 54, and the air in the top of cylinder 43 above the piston head is exhausted through the conduit 58, chamber 52 and outlet conduit 57 to permit movement of the piston 39.

It will be seen, therefore, that upon energization of the electro-magnetic solenoid unit 42, the valve plate 37 is lifted from its seat and the conveyor conduit is placed in communication with atmosphere through the scavenger valve 22. The diameter of section 34 is preferably made at least as great as that of the end 31 of the conveyor conduit, and, consequently, when the valve plate 37 is lifted from its seat, air is drawn into the conveyor conduit through the scavenger valve 22 instead of through the end 31, the material inlets communicating with the discharge means 19 being thus by-passed by an ash-free stream of air which is drawn up the riser section 28 and into the separator 22. The ash-free stream of air cleans out or scavenges the ash which is suspended in the air in the riser section 255 when the valve plate 37 is lifted from its seat, and, consequently, when the flow of air stops, the air in the riser is ash free, no ash remaining thereon to settle at the bottom of the riser and to accumulate there until it forms an obstruction to any flow of air through the conveyor conduit. After the flow of air stops, the gate 38 opens and the collected ash is discharged. If desired, the cut-off gate 32 may be employed to positively cut-off the flow of air through conveyor section 26, but this is not necessary for eflicient operation.

After the ash is discharged the flow of air is resumed and the electro-magnetic solenoid unit is ale-energized. Consequently, the valve plate 37 is returned to its seated position on flange 36 in the manner described hereinabove, the flow of air through the scavenger valve 22 being thus shut off and the flow thereof throu h the end 31 being resumed. In this connection it will be noted that the flow of air through the scavenger valve 22 preferably is not cut off until after the flow through the conveyor conduit is restored to its full volume and velocity.

Although the means for actuating valve plate 37 has been shown and described as a pneumatic piston 39 controlled by a valve 41 which is actuated by an electromagnetic solenoid unit 42, any other means which will afford the required mechanical action of valve plate 37 may be substituted therefor. Furthermore, the control means for starting and stopping the air flow through the conveyor conduit need not necessarily be operatively associated with the means for starting and stopping the exhauster 23, and the discharge gate 38 of the separator 24 may be either motor or hand operated.

It should be apparent now that a bulk materials han dling system of the vacuum type has been provided with means for effectively by-passing the material inlets and scavenging such material as may be suspended in a generally vertical section of the conveyor conduit when con veying from the material inlets ceases, the aforementioned means being effective to prevent accumulation of material at the bottom of the riser to increase the capacity of the svstem by decreasing the time required to restore the flow throu h the conveyor conduit to full volume and velocity after the fiow has been cut off, and by makin it unnecessary to manually clear out any such accumulation of material.

It should be obvious that although the apparatus herein disclosed as embodying the invention has particular utility in the construction of systems of the vacuum type for handling bulk materials such as ash, certain features are of more general application and that, therefore, it is not intended to limit the invention to the exact construction and combination herein shown and described for purposes of illustration as various modifications within the scope of the appended claims may occur to persons skilled in the art.

What is claimed as new and useful is:

1. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlet. and also including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, means positioned on the downstream side of said material inlet and aflording a second inlet for said fluid, and means operable to open and close said second inlet at a predetermined time relative to the operation of said exhaust means, said exhaust means acting when said second inlet is open to draw said fluid through the latter and said generally vertical section without said fluid being first drawn past said material inlet for entrainment of said material therein.

2. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlet including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said fluid through said conduit, means positioned on the downstream side of said material inlet and attording a second inlet for said fluid, and means operable to normally maintain said second inlet closed and to open said second inlet at a predetermined time prior to stoppage of the flow of said fluid through said conduit, said exhaust means acting while said second inlet is open to draw said fluid through the latter for scavenging the material entrained in the fluid in said generally vertical section of conduit when said second inlet is opened.

3. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, a plurality of inlets for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlets, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlets for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said fluid through said conduit, means positioned on the downstream side of said material inlets and affording a second inlet for said fluid, and means operable to normally maintain said second inlet closed and to open said second inlet at a predetermined time prior to stoppage of the flow of said fluid through said conduit, said exhaust means acting while said second inlet is open to draw said fluid through the latter for scavenging the material entrained in the fluid in said generally vertical section of conduit when said second inlet is opened.

4. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlet, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said fluid through said conduit, means positioned on the downstream side of said material inlet and affording a second inlet for said fluid having a capacity at least as great as that of the first mentioned inlet for said fluid, and means operable to normally maintain said second inlet closed and to open said second inlet at a predetermined time prior to stoppage of the flow of said fluid through said conduit, said exhaust means acting while said second inlet is open to draw said fluid through the latter for scavenging the material entrained in the fluid in said generally vertical section of conduit when said second inlet is opened.

5. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material iniet, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said fluid through said conduit, means positioned on the downstream side of material inlet and aflording a second inlet for said fluid having a capacity at least as great as that of the first mentioned inlet for said fluid, and means operable to normally maintain said second inlet closed and to open said second inlet at a predetermined time prior to stoppage of the flow of said fluid through said conduit, said exhaust means acting while both said inlets for said fluid are open to draw said fluid through said second inlet for scavenging the material entrained in the fluid in said generally vertical section of conduit when said second inlet is opened.

6. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlet, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said fluid through said conduit, valve means operable in timed relation to the flow of said fluid to cause said fluid to by-pass said material inlet for a predetermined period of time prior to the stoppage of said flow for scavenging the material entrained in the fluid in said generally vertical section of conduit at the time said by-pass means becomes effectwo.

7. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with an upstream end portion communicating with atmosphere, a generally vertical section, and an inlet for the material to be conveyed, including means operable to exhaust said conduit to thereby draw air through said open end portion, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said air through said conduit, valve means in said conduit comprising an intermediate portion thereof having an upwardly presenting inlet communicating with atmosphere, a closure member over said upwardly presenting inlet, and means for moving said member between positions wherein said upwardly presenting inlet is respectively opened and closed, said movement being in timed relation to the flow of said air to cause said air to bypass said material inlet for a predetermined period of time prior to the stoppage of said flow for scavenging the material entrained in the air in said generally vertical section of conduit at the time said upwardly presenting inlet is opened.

8. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with an upstream end portion communicating with atmosphere, a generally vertical section, and an inlet for the material to be conveyed, including means operable to exhaust said conduit to thereby draw air through said open end portion, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said air through said conduit, valve means in said conduit comprising an intermediate portion thereof having an upwardly presenting inlet communicating with atmosphere, a closure member over said upwardly presenting inlet, vertically reciprocable fluid pressure means over said member for moving said member between positions wherein said upwardly presenting inlet is respectively opened and closed, and electro-magnetic solenoid means in control of said fluid pressure means, said movement being in timed relation to the flow of said air to cause said air to by-pass said material inlet for a predetermined period of time prior to the stoppage of said flow for scavenging the material entrained in the air in said generally vertical section of conduit at the time said upwardly presenting inlet is opened.

9. In bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter being positioned on the upstream side of said material inlet, including a fluid and materials separator provided with a discharge gate for the material collected and means for controlling said gate, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, through said generally vertical section and through said separator, and also aromas including means for stopping the flow of said fluid, valve means operable to cause said fluid to bypass said material inlet, and electro-magnetic solenoid means in control of said valve means, said solenoid means being connected in electric circuit with said means for stopping the flow of fluid and with said means for controlling said discharge gate and the operation of the apparatus being timed so that said material inlet is by-passed for a predetermined period of time prior to the stoppage of said flow for scavenging the material entrained in the fluid in said generally vertical section of conduit when said by-passing commences, said gate being opened after stoppage of said flow for discharge of said material collected in said separator.

10. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlet, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for stopping the flow of said fluid through said conduit, valve means operable to cause said fluid to by-pass said material inlet, and electromagnetic solenoid means in control of said valve means, said solenoid means being connected in electric circuit with said means for stopping the flow of fluid and the operation of the apparatus being timed so that said material inlet is by-passed for a predetermined period of time prior to the stoppage of said flow for scavenging the material entrained in the fluid in said generally vertical section of conduit when said by-passing commences.

11. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the lat ter inlet being positioned on the upstream side of said material inlet, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for starting and stopping the flow of said fluid through said conduit valve means operable to cause said fluid to by-pass said material inlet, and electro-magnetic solenoid means in control of said valve means, said solenoid means being connected in electric circuit with said means for starting and stopping the flow of fluid and the operation of the apparatus being timed so that said material inlet is by-passed for a predetermined period of time prior to the stoppage of, and subsequent to the commencement of said flow.

12. In a bulk materials handling system of the vacuum type including a conveyor conduit provided with a generally vertical section, an inlet for the material to be conveyed and another inlet for the conveying fluid, the latter inlet being positioned on the upstream side of said material inlet, including means operable to exhaust said conduit to thereby draw said fluid through said inlet therefor, past said material inlet for entrainment of said material therein, and through said generally vertical section, and also including means for starting and stopping the flow of said fluid through said conduit, valve means operable to cause said flow to by-pass said material inlet, and electro-magnetic solenoid means in control of said valve means, said solenoid means being connected in electric circuit with said means for starting and stopping the flow of the apparatus being timed so that said material inlet is by-passed for a predetermined period of time, said period commencing prior to stoppage of said flow and continuing until after resumption of full flow.

References Cited in the file of this patent UNITED STATES PATENTS 1,314,677 Linton Sept. 2, 1919 2,514,333 Mylting July 4, 1950 2,639,862 Watts May 26, 1953 2,640,731 Hill June 2, 1953 

